Remote-control device for a crane

ABSTRACT

A remote-control assembly for controlling a crane or the like which completely insulates the operator of the remote-control assembly from electric shock. The remote-control assembly includes a remote-control box having a plurality of fluid valves, a converter box including a plurality of pressure switches, and a plurality of fluid lines connecting the fluid valves to the pressure switches. The pressure switches are electrically connected to an electric plug which is adapted to be connected to the electrical control box on the chassis of the crane for operating the crane.

FIELD OF THE INVENTION

The present invention relates to a remote-control unit for a crane, ashovel, or a similar machine, and more particularly, to an improvedremote-control unit for insulating the operator from electrical shock.

BACKGROUND OF THE INVENTION

Remote-control units for cranes and the like are generally well known.Typically, present remote-control systems for cranes include about 30feet of electric, multiconductor wire cable connected to a hand-held,remote-control box which contains a plurality of electrical switches.The other end of the cable is connected to a control circuit on thechassis of the crane for controlling the various operations of the boom,trolley, and hoist on the crane. In this manner, when the operatoractuates an electrical switch on the remote-control box, it energizesone of the control circuits to operate a particular component of thecrane, such as moving the boom, or moving the trolley, or moving thehoist.

Although such an arrangement is generally satisfactory from anoperational standpoint, there are certain drawbacks. For example, theremote-control box and cable, as well as the crane, are all electricallyconductive. Therefore, during operation of the crane, if the operatorinadvertently causes the boom to hit a high-voltage electric line, itwill discharge through the crane and electric cable directly to theoperator holding the remote-control box. As a result, the operatorreceives a large electrical shock and may be injured or killed. As suchhigh-voltage lines are a common occurrence at work sites which employsuch cranes, it is not uncommon for the operator of the remote-controlunit to be injured as a result of the boom inadvertently striking ahigh-voltage line.

One possible solution would be to insulate the entire remote-controlunit which is being held by the operator. However, this would make theremote-control unit too bulky. Moreover, there is no practical way tosufficiently insulate each of the individual switches on theremote-control box.

Another attempted solution has been to employ a fiber-opticremote-control unit with converters for converting the light signals toelectrical signals. However, such an arrangement has been found to betoo delicate and unreliable and prone to frequent breakdowns.

Accordingly, it would be highly desirable to provide an arrangement fora remote-control unit for a crane or the like which completelyeliminates the possibility of the operator of the remote-control unitreceiving an electric shock when the boom strikes a high-voltage line,and to provide such an arrangement which is both economical andreliable.

Broadly, it is an object of the present invention to provide an improvedremote-control unit for a crane which satisfies one or more of theforegoing objectives. Specifically, it is within the contemplation ofthe present invention to provide an improved remote-control unit for usein such devices as cranes, shovels, and the like which eliminates thepossibility of the operator of the remote-control unit being subject toan electric shock.

It is a further object of the present invention to provide an improvedremote-control unit which is completely insulated from the crane and theelectrical control circuit mounted on the chassis of the crane.

It is a still further object to provide an improved remote-control unitwhich is economical, reliable, and able to withstand tough fieldconditions and inclement weather conditions.

SUMMARY OF THE INVENTION

Briefly, in accordance with the principles of the present invention, animproved remote-control assembly or unit is provided for controllingcranes, shovels, or similar machines. Typically, the crane includes amovable boom which is pivotally mounted on the chassis of the crane sothat it can be swung in either direction. In addition, as is well knownin the art, a trolley is mounted for movement along the boom, and amovable hoist is also provided. The electrical control circuit on thechassis of the crane, as is also known in the art, includes a pluralityof electric circuits for controlling and moving the various elements ofthe crane, including the boom, trolley, and hoist. In the preferredembodiment, the remote-control unit includes a remote-control box, ahose, a converter box, and an electrical plug connected to the converterbox. The remote-control box includes a plurality of air valves, forexample, four two-way air valves. These air valves are connected by aplurality of plastic tubes running through a common plastic hose to aplurality of pressure switches mounted in the converter box. As will beexplained herein, if there are four two-way air valves in theremote-control box, the common plastic hose would have nine plastictubes extending through it, two for each air valve and one common airsupply line. In addition, the converter box would include eight pressureswitches. Each of the pressure switches is electrically conected to theelectrical plug. As in the prior art devices, the electrical plug isadapted to be plugged into the electrical control circuit forcontrolling the crane which is mounted on the chassis of the crane.

Advantageously, as a result of the present invention, there is providedan arrangement which completely eliminates the possibility of theoperator of the remote-control box receiving an electrical shock whenthe boom strikes a high-voltage line. As will be understood, when theboom strikes a high-voltage line, the electricity will discharge throughthe chassis of the crane and the electrical control circuits and theelectric lines between the plug and the converter box. However, theelectricity will not discharge through the pressure switches, or theplastic tubing, or the remote-control box connected to the plastictubing. In this manner, the operator of the remote-control box iscompletely insulated from such an electric shock.

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects, features, and advantages of the present invention willbecome apparent upon the consideration of the following detaileddescription of a presently preferred embodiment when taken inconjunction with the accompanying drawings, wherein:

FIG. 1 is a side elevational view of a crane and a remote-controlassembly connected thereto; and

FIG. 2 is a detailed view of the remote-control assembly of the presentinvention.

DETAILED DISCUSSION OF PREFERRED EMBODIMENT OF THE INVENTION

Referring now to FIG. 1, there is shown a crane 10 and a remote-controlassembly 12 embodying the principles of the present invention. As iswell known in the art, the crane 10 includes a chassis or frame 14having a rotating pedestal 16 mounted thereon. A boom 18 is provided andpivots relative to the pedestal 16. In addition, a trolley 20 is movablymounted on the bottom 18 and is provided with a cable or hoist 22 whichmay be moved up and down relative to the boom. As is also known in theart, mounted on the chassis 14 of the crane, there is provided anelectrical control box 24 which includes suitable circuitry foroperating and controlling the boom 18, the trolley 20, and the hoist orcable 22. Typically, such electrical circuitry includes four two-waysolenoid valves (not shown). One solenoid valve is for moving the boom18 up and down, a second solenoid valve is for swinging the boom to theleft or right, a third solenoid valve is for moving the trolley 20relative to the boom 18, and the fourth solenoid valve is for moving thecable or hoist 22 up and down.

As will be seen in FIG. 1, the remote-control assembly 12 includes anelectric plug 30, a line 32 connecting it to a converter box 34, and aplastic hose or line 36 connecting the converter box 34 to aremote-control box 38. As will be understood, the crane 10 and theelectrical control circuit 24 for controlling the crane are conventionalfeatures well known in the art and need not be described in furtherdetail. The present invention only concerns the remote-control assembly12, and specifically the elements between remote-control box 38 andelectric plug 30.

Referring now to FIG. 2, a more detailed view of the remote-controlassembly 12 is provided. As will be noted, remote-control box 38includes four two-way air valves 40, 42, 44, and 46, preferably of thetoggle type, as shown. Each of the valves is connected to two air lines,such as 46a, 46b, and a common air supply line 48. As will beunderstood, line 46a is for controlling one particular function, such asswinging of the boom 18 to the left, whereas the other line 46b would befor controlling the boom to swing in the other direction. Basically, thefour air valves 40, 42, 44, and 46 replace the four electricaltwo-position switches employed on remote-control boxes in the past. Thetwo air lines from each air valve and the one common air supply line 48form a total of nine air lines. Such air lines can be formed of anynon-conductive material, and preferably are formed of plastic. Thesenine plastic lines extend through common hose 36 which is also formed ofa non-conductive material, such as plastic.

Referring now to converter box 34, it shows the air or fluid lines 46a,46b, etc., extending into the converter box, with each line beingconnected to a different one of the eight pressure switches 50, 52, 54,56, 58, 60, 62, and 64 mounted in converter box 34. For example, fluidline 46a is connected to pressure switch 50 at terminal 50a. Inaddition, common fluid line 48 extends into converter box 34 and isconnected to a pressure regulator 70 which is connected to a source ofcompressed air (not shown). For example, the source of compressed aircan be right on the crane 10 which is used to supply compressed air forother functions on the crane. Preferably, the source of compressed airshould be at 120 psi, and the pressure regulator 70 should supplycompressed air via line 48 to the air lines 46a, 46b, 44a, etc., at 30psi in order to operate the pressure switches.

Each of the pressure switches 50 to 64 includes two additional terminalsfor electrical connections. For example, pressure switch 50 includes aterminal 50b which is adapted to be connected to a common electricalwire 72. As will be seen, wire 72 is adapted to be connected to oneterminal of each of the pressure switches, and then wire 72 extends intothe electric plug 30. Similarly, each pressure switch includes a thirdterminal, such as terminal 50c, so that each pressure switch iselectrically connected to plug 30 by another electric line, such as line50d. As explained above, electric plug 30 is adapted to be plugged intocontrol box 24 mounted on the chassis 14 of the crane 10.

Referring now to FIG. 2, operation of the remote-control assembly 12 ofthe present invention will now be provided. When a particular functionof the crane is required, such as pivoting the boom 18 to the left orright, one of the air valves, such as air valve 46, is moved to one ofits two positions. As a result, compressed air is supplied by commonfluid line 48 to one of the fluid lines connected to the air valve, suchas fluid line 46a. Then, compressed air flows through fluid line 46a andoperates to actuate one of the pressure switches, such as pressureswitch 50. As a result, the particular pressure switch which isoperated, then operates to complete an electrical circuit between thepressure switch and the electric plug 30. Then, the particularelectrical control circuit in control box 24 for moving the boom isoperated in a conventional manner. More particularly, one of thesolenoid valves is actuated to cause the boom to move, as is known inthe art.

Although the present invention has been described using compressed airand air valves, it should be understood that other fluids may beemployed, such as oil. In such an arrangement, fluid valves would beconnected to fluid lines, instead of air valves connected to air lines.In addition, any type of conventional pressure switch may be employed,as long as it has the capacity of being operated by a fluid to close apair of electrical contacts to complete a circuit. For example, thepressure switch may include a diaphragm 50e which is moved by theincoming fluid to close electrical contacts 50f and 50g.

In view of the foregoing, it will be appreciated that there has beenprovided in accordance with the present invention a simple, economical,and reliable device for completely insulating the operator of theremote-control box 38 from electric shock. That is, there is 30 feet ofplastic cable 36 extending between the electrical lines in converter box34 and the remote-control box 38 which is being held by the operator. Inthis manner, the operator of the remote-control box is completelyinsulated from any electric shock which may be discharged from the crane10 into the electrical control circuit 24, the electric plug 30, and theconverter box 34. In fact, the plastic tubing 36 has been tested towithstand a 70,000 volt charge.

A latitude of modification, change, and substitution is intended in theforegoing disclosure, and in some instances, some features of theinvention will be employed without a corresponding use of otherfeatures. Accordingly, it is appropriate that the appended claims beconstrued broadly and in a manner consistent with the spirit and scopeof the invention herein.

What is claims is:
 1. A remote-control assembly for controlling a craneor the like having a movable member, wherein said crane includes anelectrical control circuit for controlling said movable member,comprising:a remote-control box including a plurality of fluid valvesand means for operating said fluid valves; a converter box including aplurality of pressure switches; each of said pressure switches includinga diaphragm having at least one electrical contact mounted thereon; eachof said pressure switches being formed by a separate housing forenclosing said diaphragm and said electrical contact; a plurality offluid lines connecting said fluid valves to operate the diaphragms ineach of said pressure switches; and a plurality of electric linesconnecting the electrical contacts of said pressure switches to saidelectrical control circuit on said crane for operating said movablemember.
 2. A remote-control assembly in accordance with claim 1, whereinsaid remote-control box includes a plurality of two-way air valves.
 3. Aremote-control assembly in accordance with claim 1, wherein saidconverter box includes a pressure regulator for supplying compressed airto said pressure switches.
 4. A remote-control assembly in accordancewith claim 1, wherein said plurality of fluid lines is formed of plastictubes for supplying air.
 5. A remote-control assembly in accordance withclaim 4, wherein said plurality of plastic tubes is housed in a commonplastic hose.
 6. A remote-control assembly in accordance with claim 1,further including an electric plug connected to said plurality ofelectric lines adapted to be plugged into said electrical controlcircuit. .Iadd.
 7. A remote-control assembly for controlling a crane orthe like having a movable member, wherein said crane includes anelectrical control circuit for controlling said movable member,comprising:a remote-control box including a plurality of fluid valvesand means for operating said fluid valves; a converter box including aplurality of pressure switches; each of said pressure switches includingmovable means having an electrical contact; each of said pressureswitches being formed by a separate housing for enclosing said movablemeans and said electrical contact; a plurality of fluid lines connectingsaid fluid valves to operate the movable means in each of said pressureswitches; and a plurality of electric lines connecting the electricalcontacts of said pressure switches to said electrical control circuit onsaid crane for operating said movable member. .Iaddend. .Iadd.
 8. Aremote-control assembly for controlling a crane or the like having amovable member, wherein said crane includes an electrical controlcircuit for controlling said movable member, comprising: aremote-control box including a plurality of fluid valves and means foroperating said fluid valves; a converter box including a plurality ofpressure switches; each of said pressure switches including anelectrical contact switch having movable means activated by airpressure; each of said pressure switches being formed by a separatehousing for enclosing said electrical contact switch; a plurality offluid lines connecting said fluid valves to operate the movable means ineach of said pressure switches; and a plurality of electric linesconnecting the electrical contacts of said pressure switches to saidelectrical control circuit on said crane for operating said movablemember.